Automatic centrifugal laundry drier



8 Sheets-Sheet 1 Filed March 28, 1963 on O OOOOOOOOOODQ FIG] INVENTOR. EEIIYHOL 0 NflC/f A 770PM Oct. 11, 1966 R. MACK AUTOMATIC GENTRIFUGAL LAUNDRY DRIER Filed March 28 1963 8 Sheets-Sheet 3 Oct. 11, 1966 R. MACK AUTOMATIC CENTRIFUGAL LAUNDRY DRIER 8 Sheets-Sheet 5 Filed March 28, 1963 INVENTOR. EA'M/bWZ 0 Mine may! g 4 774 9 V Oct. 11, 1966 R. MACK AUTOMATIC CENTRIFUGAL LAUNDRY DRIER 8 Sheets-Sheet 6 Filed March 28, 1963 INVENTOR. REl/YHOL D MACK Oct. 11, 1966 R. MACK 3,

AUTOMATIC CENTRIFUGAL LAUNDRY DRIER Fil ed March 28, 1963 a Sheets-Sheet 7 r-wm-rrvi INVENTOR. Elf/M904 0 MAC {Karl Oct. 11, 1966 R. MACK 3,

AUTOMATIC CENTRIFUGAL LAUNDRY DRIER Filed March 28, 1963 8 Sheets-Sheet 8 REINHOLD MACK INVENTOR.

BY fp AGENT United States Patent 3,277,583 AUTOMATIC CENTRIFUGAL LAUNDRY DRIER Reinhold Mack, Jahnstrasse 144, Goppingen, Wurtternberg, Germany Filed Mar. 28, 1963, Ser. No. 268,678

Claims priority, application Germany, Mar. 31, 1962, M 52,351; Oct. 24, 1962, M 54,594; Feb. 28, 1963, M 55,927

27 Claims. (Cl. 34-58) My present invention relates to an automatic laundry drier of the centrifugal type in which a generally cylindrical drum with a perforated peripheral wall is spun at high speed about its axis to squeeze Water from a load of wet garments or the like.

Conventional driers :of this type are only partially effective because of the limited rotary speed to which their drums can be subjected, particularly in the case of household machines utlizing single-phase, alternating-current motors. Though the centrifugal force can be increased by enlarging the drum diameter, restrictions on size and cost make major improvements along these lines impractical. Moreover, a large centrifugal force tends to urge the load against the inner wall surface of the drum with such pressure as to form sealed fluid pockets therein from which the water can be expelled only with difliculty. Attempts to promote drying by the introduction of hot air into the drum also have been only partly successful since the compacted laundry articles are not readily penetrated by the heated fluid so that only an exposed inner surface of the garments is more thoroughly dried.

The general object of my present invention is to provide means in a centrifugal laundry drier for more efiectively utilizing a supply of drying fluid, such as hot air, whereby the aforementioned disadvantages are avoided.

This object is realized, pursuant to the invention, by the provision of duct members forming an array of peripheral channels along the drum wall, the channels being closed toward the outside but communicatingwith the interior of the drum through :a series of perforations whereby the heating fluid admitted into the channels can fiow, at least in part, into the drum through the interstices of the garments clinging to this wall before escaping outwardly through its perforations upon another traverse of the load. Thus the Wet articles are thoroughly exposed to the hot fluid so that the drying effect is intense. As the load gives off moisture, it adheres less closely to the drum wall whereby drying is further accelerated. In this manner, by virtue of the present improvement, garments ready for ironing (ie with a moisture content of about or less) can be removed from [the drum after a moderately long drying cycle at reasonable speed (eg, of 1400 or 2800 r.p.m.).

The forced circulation of hot air, serving as the drying fluid, may be brought about by a variety of means but is advantageously effected by the rotation of the drum itself. To this end I provide, pursuant to a further feature of my invention, an array of angularly spaced impeller elements which drive the air through the channels and into the drum under a pressure commensurate With its rate of spin. It will usually be found expeditious to mount the drum for rotation about a vertical axis and to dispose the impeller elements, or at least one of several sets of them, in an angularly spaced array near the top of the drum adjacent the channel inlets or directly con nected thereto; these impeller elements take the form of substantially radial rotary vanes, or air scoops whose open ends face in the direction of drum rotation.

The duct members forming the channels advantageously are of approximately semicylindrical shape and positioned next to the outer or the inner surface of the 3,277,583 Patented Oct. 11, 1966 ice drum wall; the latter arrangement will be preferable since these members then also form inner ribs preventing the garments from clinging too tightly to the peripheral drum surface whereby permeation by the drying air is further facilitated even in the early phase of operation. The duct members may extend vertically, horizontally or at an inclination, e.g. along approximately helical lines, and may be made of a variety of materials; thus, for example, they could consist of sheet metal or they may be molded integrally with the drum body from suitable plastics. If disposed vertically or inclinedly, they preferably have their inlets at'the top and their outlets at the bottom, these outlets opening again into the interior of the drum above the closed bottom wall of the latter.

A drier according to the invention may be conveniently combined with a Washer in a common housing or may even be convertible into a washer through appropriate alteration of its drum speed and/ or a changeover from a vertical to a horizontal drum position.

The invention will be described in greater detail with reference to the accompanying drawing in which:

FIG. 1 is an elevational view, in longitudinal section, of a centrifugal drier according to the invention;

FIG. 2 is an axial sectional view through a drum forming part of the drier of FIG. 1;

FIG. 3 is partly a top view and partly a transverse section of the drum shown in FIG. 2;

FIG. 4 is a top view, again partly in section, of an impeller attachment secured to the drum of FIGS. l-3;

FIG. 5 is a view similar to FIG. 1, showing another embodiment;

FIG. 6 is a perspective top view of a slightly modified drum of the general type shown in FIG. 5;

FIG. 7.is a view similar to FIG. 6, showing a further modification;

FIG. 8 is a perspective bottom view of still another form of drum according to the invention;

FIG. 9 is a view similar to FIG. 5, illustrating a further modification of that system;

FIG. 10 is again a view similar to FIGS. 1, 5 and 9, showing a combination washer/drier embodying the in vention; and

FIG. 11 is a perspective detail view of a drum representing yet another embodiment.

The system shown in FIGS. 1-4 comprises a housing 1, roughly in the shape of an upright cylinder, having a drum 4 coaxially disposed therein. ported on a shaft 3 of a drive motor 2 of conventional construction and operating speed, e.g. a single-phase motor of 1400 or 2800,r.p.m. Motor 2, resting on the base of the housing, supports with the aid of several studs 50 (only one shown) a splash plate 51 which partitions the housing into a lower motor compartment and an upper drum compartment; the drum compartment is provided, just above the splash plate 51, with a drain 32 whose width is sufficient to insure that the air pressure within the housing, externally of drum 4, is maintained at or near atmospheric level so as not to impede the discharge of air and water from the drum.

Housing 1 is provided at its top with a circular access opening 53 constituting a door for the introduction of a wet charge and its subsequent removal in a semidried state. This access opening is overlain, during the drying operation, by a cover 5 shown in its position of closure, the cover being hinged to the housing at 6 and being progided with a handle 7 to facilitate its removal from the oor.

As shown in greater detail in FIGS. 2 and 3, drum 4 is provided at its inner peripheral wall surface with a set of angularly spaced vertical chanels 8 formed by semicylindrical duct members 23. In the particular embodi- The drum 4 is sup- 3 ment illustrated, eight such channels spaced 45 apart are present. The duct members 23 span imperforate portions of the drum wall but are themselves for-med with bores 9 disposed in two vertical rows 90 apart (with reference to the semicircular cross-section of the ducts) so as to face in mutually perpendicular directions on opposite sides of a radial plane bisecting the duct. Between the duct members 23 the peripheral drum wall is provided with numerous apertures 12 serving for the outflow of squeezed-out water and drying air. The chan nels 8 have upper inlets 31 and are provided at their lower ends with radial horizontal extensions 26 formed by short horizontal legs 24 which may be integral with the duct members 23 and are of substantially the same shape; they have, however, only one row of upwardly facing perforations 9. The members 23, 24 may be cemented or otherwise secured to the drum 4 if not formed integr-ally therewith. The solid bottom wall of the drum, separating the duct extensions 24, is shown concentrically corrugated and provided on its underside with a recess 25' receiving a mounting plate 3' seated on shaft 3 as shown in FIG. 1. The corrugations of bot-tom 25 constitute further paths 25" (besides bores 9, 9') by which air entering the channels 8, 26 from above, via inlet ends 8', can stream into the interior of the drum, the remaining air finally emerging from the open inner ends of channel portions 26 within a tubular central boss 11. Drum 4 is formed at the top with .a constricted neck encompassing the channel inlets 8', this neck being provided with lugs 16 engageable by a bayonet coupling on a header 13 removably attached thereto.

Header 13, which is slightly smaller than the access opening 53 so as to pass readily through it, includes a bottom plate 14 provided with an array of eight generally semicircular port 31 which register with respective channel inlets 8' directly below plate 14. The header is formed at its top with a central flange 27 terminating in an outwardly bent lip. A similar but inversely disposed flange 28 depends from a sleeve 17 fixedly secured by legs 52 to the cover 5. The interior of sleeve 17 accommodates a supplemental blower, comprising a flan 19 and a motor 20 therefor, as well as heating means shown here diagrammatically as a set of coils 18 above fan 19. A set of rotary impeller vanes 15 are generally radially disposed within header 13 and rise inside flange 27 to the level of its upper lip. In similar fashion, a set of fixed guide vanes 21 are radially arranged inside the flange 28 so as intermittently to register with the vanes 15 when the drum is in motion. In the particular embodiment illustrated, eight rotary vanes 15 are disposed adjacent respective ports 31, trailing them in the direction of drum rotation (see arrow A in FIG. 4), with a like number of vanes 21 equispaced above them. A small annular air gap s (FIG. 2), e.g. about 12 mm. or half an inch wide, separates the out-turned lips of flanges 27 and 28 from each other to allow for any slight wobbling of header 13 that may occur during its rotation; the same distance, of course, separates the two sets of vanes 15, 21 from each other. At the same time the gap s minimizes the direct outflow of heated air from the interior of sleeve 17 into the space surrounding the drum 4.

The cover 5 also has a set of lateral vents 22 through which, in the operation of the drier, atmospheric air is drawin in by the combined action of fan 19 and rotary vanes 15. This air, heated by the coils 18, is propelled into the channels 8, 26 from which a substantial portion of its streams into the interior of drum 4 via bores 9 and 9'. Especially the air flowing in through bores 9 permeates the garments that cling to the sides of the drum, thereby absorbing moisture from them and promoting their drying. As the operation progresses, the articles within the drum become drier and consequently more permeable whereby the air flow through the perforation-s 9 is correspondingly increased. The residual air passes inwardly over the paths 25" and through the boss 11, thus all the air introduced into the channels at 31, 8' eventually flows into the drum firom the sides or the bottom thereof. This air, with its entrained moisture, finally escapes from the drum through its peripheral apertures 12 and leaves the housing 1 by way of drain 3 2. It will be noted that the duct members 23 form inwardly projecting ribs which reduce the adherence of the wet garments to the drum wall and help separate them from that wall after some of their initial water content has been driven off. Naturally, the degree of drying obtainable by the illustrated arrangement depends on the length of the treatment and, to a centain extent, upon the intensity of circulation and the temperature of the air as heated by the coils 18. For reasons of safety it will be desirable to provide a circuit breaker (for example within the hinge 6, compare FIG. 5), to deener-gize the motors 2 and 20 as well as the heater 18 when the cover 5 is opened by its handle 7.

The embodiment shown in FIG. 5 is generally similar to the one illustrated in FIGS. 1-4 and like reference numerals, with a 1 added in the position of the hundreds digit, have been used to designated corresponding or equivalent elements which therefore need not be further described. The duct members 123 inside drum 104 have upper terminations 110 which are bent forwardly in the direction of rotation and pass outwardly through cutouts 119 in the restricted neck 130 of the drum to form external air scoops 111 thereon. The lower branches 126 of the ducts terminate, short of the drum axis, in perforated cups 127 adjacent the rim of a central boss 114 by which the drum bottom 125 is secured to mounting plate 103' by means of a bolt 10 The embodiment of FIG. 5 also has a modified cover whose air vents are formed by bucket-shaped upward projections stamped out of the metallic cover material. The cover is hollow and bonded at its underside by a. screen 115, its side wall being advantageously lined by a thermally insulating layer 116 (e.g. of asbestos) which, of course, could also be extended over all or part of the upper cover plate bearing the vents 122. A heater 118, for example in the form of one or more spirally wound resistance coils as diagrammatically illustnated, is disposed within cover 105 to heat the air drawn in through the vents 122.

.As the drum 104 rotates, the hot air is picked up by the scoops 11-1 and forced into the channels 108 and 126, the further procedure being the same as in the preceding embodiment. It will be. understood that the higher air pressure within drum 104 opposes the direct entrance of air into the drum through its open top.

Cover 105 is shown provided at its top with a central stirrup 107 engaged, in its position of closure, by a horizontally 'swin'gable handle 106 which is pivoted to the housing 101 at 106'. As described in connection with FIG. 1, handle 106 may operate a safety switch which has been shown schematically at 154 and serves to disconnect heater 118 as well as motor 102 from their source of electric power. It will be understood that this safety switch, which of course may also be provided in the remaining embodiments, is independent of any conventional timer mechanism which turns the motor or motors on and off and which, advantageously, may be designed to cut out the heater 18 or 118 a minute or two before the drive motor of the drum is stopped, thereby insuring a sufficient cooling of the housing cover by the aspirated air to make it safe to the touch.

FIG. 6 shows another view of the drum 104 wherein, however, the terminations of the ducts 108 have been somewhat modified to join these ducts angularly rather than merging tangentially with them as is the case with the terminations 110 in FIG. 5.

Another modification is illustrated in FIG. 7 Where the drum 104 is internally provided with ducts 108' extending along helicoidal lines over substantially half a E turn. The lower horizontal branches 126 of the ducts extend radially as in the preceding embodiments.

FIG. 8 shows a drum 204, topped by a peripheral array of air scoops 211, which in its internal construction may be similar to drum 104 of FIG. 7 (note distribution of perforations 212) but which in addition has its bottom wall 225 provided on its underside with a set of radially extending fan blades 233. The peripheral drum wall is extended below the bottom wall 225 to form an annular skirt 226 to which the blades 233 are secured, these blades projecting downwardly beyond the skirt 226 so as to create a radially outward air circulation which promotes the outflow of air and water from the wall perforations 212. Drum bottom 225 is formed with an annular ridge 234 surrounding a central depression 237 adapted .to receive a drive shaft and mounting plate as illustrated in FIG. 1; depression 234 is reinforced by radial ribs 235. The blades 233, which terminate at the rim of depression 237, may be welded to the bottom wall 225 or otherwise secured thereto. Naturally, similar blades may also be provided on the other drum types herein disclosed.

FIG. 9 shows a system generally similar to that of FIG. 5, but with certain modifications at the bottom end of the drum 304 and at the cover 305. This cover, accommodating the heater 318, is provided at its underside with an imperforate plate 315 replacing the screen 115 of FIG. 5. Plate 315, which may be made of or lined with a suitable refractory material, is secured to the peripheral cover wall 316 by angularly spaced stays 355 'so as to'leave a nearly continuous annular slot 356 between itself and wall 316. Air aspirated by the rotating scoops 311 into ducts 308, entering the hollow cover 305 through its vents 322, is deflected by the solid plate 355 away from the open mouth of drum 304 and toward the entrance ports of the scoops 311.

The vertical ducts 308 in FIG. 9 terminate at a space confined between the drum bottom 325 and an annular false bottom 324, perforated at 309', which rests on bottom wall 325 by a downwardly converging collar 328, of frustoconical configuration, provided with air-outlet slots 327 along its inclined generatrices. Col-lar 328 registers with the central boss 314 secured to the mounting plate 303' by bolt '303".

In FIG. 10 I have illustrated a drum 404 wherein the channels 408, 426 are provided not internally but externally of the peripheral drum wall. These channels are formed by generally semicylindrical members 423 which, however, are imperforate to prevent any outward escape of the heated air circulated therein. The channels 408, 426 communicate with the interior of the drum through perforations 409 in the drum wall as well as perforations 409' on the drum bottom; at the top they again terminate in air scoops 411.

The drum 404 is internally reinforced by he-licoidal ribs 440 which help loosen the garments from its inner wall surface as previously described with reference to the inner channel members. Cover 405a of housing 401 is generally similar to the covers 105 and 305 of FIGS. 5 and 9.

Whereas the drum illustrated in FIGS. 1-9 may be positioned in an individual housing or in the common housing with a washing machine, drum 404 is adapted to be used alternately as a washer and as a drier. For this purpose its motor 402 with drive shaft 403 is shown mounted on a swingable platform 441 pivoted at 443 to a bifurcate supporting bracket 442 rising from the bottom of the housing. The swinging of drum 404 from its vertical drying position (solid lines) to its horizontal washing position (dot-dash lines) may be carried out with the aid of a crank 444, rigid with pivot shaft 443, which is articulated via a link 445 to a hand lever 446. The latter is fulcrumed on a block 447 which contains a switch for controlling the speed changer 448 of the motor, thereby shifting from a relatively slow rotary speed in the horizontal position to a high-speed spin in the vertical drying position. An auxiliary door with cover 4951? is provided on the side of the housing 401 for giving access to the drum in its washing position.

FIG. 11 shows, by way of further modification, a drum 504 wherein the aerating channels 508a, 508k extend in the form of axially spaced horizontal rings along the inner periphery of the drum. These channels communicate with an external array of air scoops 511a, 5111) and, as in the preceding embodiments, are provided with bores 509 to discharge the circulating air into the interior of the drum.

It is to be understood that the various features forming part of the several illustrated embodiments may be used jointly, to the extent of their compatibility, e.g. by arranging the external channels of FIG. 10 in helical or annular form, tiltably mounting the drums of the remaining figures and/or providing impeller-type vanes (15, FIGS. 1-4) in lieu of the air scoops shown in FIGS. 5-11. These and other modifications are believed to be readily apparent to persons skilled in the art and are intended to be embraced in the spirit and scope of the invention as defined in the appended claims.

I claim:

1. An automatic laundry drier, comprising a housing, a generally cylindrical drum mounted in said housing for rotation about a substantially vertical axis, drive means on said housing for rotating said drum about said axis, said drum being provided with an apertured peripheral wall, duct means forming peripheral channels along said wall, said duct means being provided with perforations opening peripherally into the interior of said drum and forming inlets for said channels communicating with a source of drying fluid near the top of said drum and outlets for said channels communicating with the interior of said drum substantially at the bottom thereof, and forced circulation means for said drying fluid at said inlets operable at least during rotation of said drum.

2. An automatic laundry drier, comprising a housing, a generally cylindrical drum mounted in said housing for rotation about a substantially vertical axis, drive means in said housing for rotating said drum about said axis, said drum being provided with an apertured peripheral wall, duct means forming peripheral channels along said wall, said duct means being provided with perforations opening peripherally into the interior of said drum and forming inlets for said channels communicating with a source of drying fluid near the top of said drum and outlets for said channels communicating with the interior of said drum substantially at the bottom thereof, and means including an array of angularly spaced impeller elements on said drum for propelling said drying fluid via said inlets through said channels dun'ng rotation of said drum.

3. An automatic laundry drier, comprising a housing, a generally cylindrical drum mounted in said housing for rotation about a substantially vertical axis, drive means on said housing for rotating said drum about said axis, said drum being provided with an apertured peripheral w-all, duct means forming peripheral channels along said wall, said duct means being provided with perforations opening peripherally into the interior of said drum and forming inlets for said channels communicating with a source of drying air and with the interior of said drum, and means including an array of angularly spaced impeller elements on said drum for propelling said drying air via said inlets through said channels during rotation of said drum.

4. A drier as defined in claim 3 wherein said drum is provided with an access opening at its top, said housing having a removable cover overlying said access opening, said channels having inlets communicating with the interior of said housing around the rim of said access opening, said impeller elements being arrayed along said rim.

5. A drier as defined in claim 4, further comprising heating means for said drying air in said housing above said impeller elements.

6. A drier as defined in claim 4 wherein said cover is provided with air holes leading into the surrounding atmosphere, said holes constituting said source of drying air.

7. A drier as defined in claim 6 wherein said cover includes a top plate provided with said air holes, a thermally insulated peripheral wall element and a bottom screen enclosing a chamber, and comprising heating means for said drying air in said chamber, said bottom screen closely overlying said access opening in a closure position of said cover.

8. A drier as defined in claim 4, further comprising supplemental blower means independent of said drum above said impeller elements.

9. A drier as defined in claim 4 wherein said drum is provided with a centrally apertured lid attached to said drum just below said access opening and removable therethrough from said drum, said inlets being spacedly disposed below said lid, said impeller elements being carried on the underside of said lid.

10. A drier as defined in claim 9, further comprising a perforated screen plate carried on said lid beneath said impeller elements adjacent respective ones of said inlets.

11. A drier as defined in claim 9 wherein said impeller elements are a set of rotary vanes extending generally radially inwardly from said rim past the circumference of the central aperture of said lid.

12. A drier as defined in claim 11 wherein said source of drying air includes a cylindrical sleeve carried on said cover and communicating through it with the atmos phere, said sleeve registering with said central aperture and being coaxial with said drum in a closure position of said cover, said sleeve being provided with a set of stationary vanes closely spaced from the inner ends of said rotary vanes extending below said central aperture.

13. A drier as defined in claim 12 wherein said sleeve and said lid are provided with coextensive circular flanges axially separated by a small annular gap, said inner ends of said rotary vanes rising to the level of said gap.

14. A drier as defined in claim 4 wherein said duct means comprises a set of generally semicylindrical channel members extending along imperforate peripheral wall portions of said drum within the latter.

15. A drier as defined in claim 14 wherein said drum has a closed bottom wall, said channel members being provided with substantially horizontal lower extensions carried by said bottom wall and terminating in at least partly open inner extremities spaced from the drum axis.

16. A drier as defined in claim 14 wherein said channel members are substantially semicircular in cross-sec tion and are provided with at least two rows of perforations spaced apart along said cross-section by substantially 90.

17. A drier as defined in claim 14 wherein said drum has a closed bottom wall and a perforated false bottom being provided with a downwardly converging frustoconical central collar resting on said bottom wall, said collar having slots opening upwardly into the interior of the drum, said channel members opening into the space between said false bottom and said bottom wall.

18. A drier as defined in claim 14 wherein said channel members extend substantially vertically along said peripheral wall portions.

19. A drier as defined in claim 14 wherein said channel members extend generally helically along said peripheral wall portions over substantially half a helical turn.

20. A drier as defined in claim 3 wherein said duct means comprises a set of generally semicylindrical imperforate channel members extending along perforate peripheral wall portions of said drum outside the latter, said drum being provided with internal ribs along its peripheral surface.

21. A drier as defined in claim 3 wherein said impeller members are a set of peripherally spaced air scoops projectingly disposed at the top of said drum, said scoops communicating with respective channels and having entrance ports facing in the direction of rotation of the drum.

22. A drier as defined in claim 21 wherein said duct means comprises a set of generally semicircular channel members having inlet ends respectively merging with said scoops.

23. A drier as defined in claim 21 wherein said cover has a top plate provided with air holes leading into the surrounding atmosphere and constituting said source of drying air, said cover further having an imperforate bottom plate spaced from said top plate and forming a nearly continuous annular air gap with the remainder of said cover near the rim of said access opening, thereby deflecting descending air outwardly past said rim toward said scoops.

24. A drier as defined in claim 21 wherein said duct means comprises at least one substantially horizontal perforated annular channel member extending along the inner peripheral wall surface of said drum and communicating at angularly spaced locations with said scoops.

25. A drier as defined in claim 3 wherein said drum has a closed bottom Wall provided on its underside with a set of substantially radial fan blades.

26. A drier as defined in claim 25 wherein said botttom wall is formed with a central boss having mounting means, said drive means including a shaft engaged by said mounting means, said fan blades reaching inwardly substantially to the rim of said boss.

27. A drier as defined in claim 4 wherein said housing -is provided below the level of said drum with a drain of suflicient width to maintain the air pressure within said housing outside the drum substantially at atmospheric level.

References Cited by the Examiner UNITED STATES PATENTS 1,087,528 2/1914 Cassirer 34-58 1,550,060 8/1925 Demat-os 348 1,687,829 10/1928 Clark 34-58 2,974,422 3/1961 Hobbs 34-58 FOREIGN PATENTS 537,078 4/ 1955 Belgium. 1,225,508 2/1960 France. 1,080,057 4/ 1960 Germany.

FREDERICK L. MATTESON, 111., Primary Examiner.

NORMAN YUDKOFF, Examiner.

JOHN J, CAMBY, Assistant Examiner. 

1. AN AUTOMATIC LAUNDRY DRIER, COMPRISING A HOUSING, A GENERALLY CYLINDRICAL DRUM MOUNTED IN SAID HOUSING FOR ROTATION ABOUT A SUBSTANTIALLY VERTICAL AXIS, DRIVE MEANS ON SAID HOUSING FOR ROTATING SAID DRUM ABOUT SAID AXIS, SAID DRUM BEING PROVIDED WITH AN APERTURED PERIPHERAL WALL, DUCT MEANS FORMING PERIPHERAL CHANNELS ALONG SAID WALL, SAID DUCT MEANS BEING PROVIDED WITH PERFORATIONS OPENING PERIPHERALLY INTO THE INTERIOR OF SAID DRUM AND FORMING INLETS FOR SAID CHANNELS COMMUNICATING WITH A SOURCE OF DRYING FLUID NEAR THE TOP OF SAID DRUM AND 